Weather will likely play an important role when you plan your trip to Parnaíba, but bear in mind that cheaper options are usually available when the weather isn’t as good. The hottest months are usually September and October, with an average temperature of 28°C, while the coldest months are July and June, with an average of 27°C. The rainiest months in Parnaíba are April, March, February and May, with each month seeing an average of 250 mm of rainfall.